17) compare the three scenarios below. which scenario would natural selection most likely work? a) an island with lizards that all look alike and are all eating the same food. b) a population of salmon with different skin colors that attract mates. c) a population of parakeets that have the same sized beak. 20) a new species of penguins is created, which of the following could cause this to happen? a) an earthquake has happened to divide some arctic land and over time one penguin species became two different species that could no longer mate and reproduce. b) a new predator moved into the environment lowering the number of the overall population of the penguins. c) a sudden warming began melting the ice in the region causing the penguins to migrate further north. 21) variation in a trait is a required condition for natural selection to act on a population for that trait. assuming a population of organisms started with only one form of a trait, what is one way variation in the trait be introduced into the population? a) mutations b) fossils c) there is no way to add variation to the population.

Answer 17: B). A population of salmon with different skin colors that attract mates.

The natural selection is a phenomena of differential survival and reproduction, the organisms that have better phenotypic trait are likely to survive and reproduce in the adverse environment. The population of salmon with different skin colors that attract the mates is the most likely scenario of natural selection because in the competition among members of the salmon in order to obtain their mates. The members that have a better phenotypic trait that is a color which is being more attractive for members of the opposite sex, likely to get the mate and reproduce.

20: A) An earthquake has happened to divide some arctic land and over time one penguin species became two different species that could no longer mate and reproduce.

Speciation is a natural phenomena in which a new species is formed from the existing parent species when some of the members of the population of the species get separated by geographic, behavioral and biological barriers. Such individuals because of these barriers do not inbreed resulting in the condition of reproductive isolation.

An earthquake has happened to divide some arctic land and over time one penguin species became two different species that could no longer mate and reproduce is an example of the speciation in the penguin population. The division of the land because of the earthquakes will separate the penguin population in two distinct lands. The separated land populations will evolve new traits and will be developed as new species.

21: A). Mutations

A mutation is a alteration or a change that occurs at either at a single base or the entire genome of the organism. This change brings the variation in the trait or particular characteristic of the organism. These variations can be transmitted to the population by sexual mode or reproduction and inheritance.

the answer is d. chordata